问题描述: 当cos^2x-cos^2y=√3/2时,求sin(x+y)×sin(x-y) 1个回答 分类:数学 2014-10-26 问题解答: 我来补答 ∵ cos^2x-cos^2y=(cosx-cosy)(cosx+cosy=)= -2(sin(x/2-y/2))(sin(x/2+y/2))(cos(x/2-y/2))(cos(x/2+y/2))= -sin(x-y)sin(x+y)=√3/2∴sin(x-y)sin(x+y) = -√3/2 展开全文阅读